To load an animated sequence into a standin:

• In the Attribute editor for the StandInShape, under File/Frame, your Path should be something like example.####.ass (you must use four # symbols for the frame number pattern)
• Enable Use Frame Extension
• In the Frame box, type “= frame” without the quotation marks, and press ENTER. That creates an expression that uses the current frame number to specify which ASS file to load.